3. 识别AprilTags例程讲解#

1. 概述#

AprilTags 是一种视觉标记系统，用于计算机视觉应用中进行定位、识别和跟踪。由 April Robotics 开发，AprilTags 是一种非常高效的二进制识别标签系统，具有广泛的应用场景，尤其在机器人技术和增强现实领域中表现突出。

CanMV支持OpenMV算法，支持识别AprilTags，相关接口为find_apriltags

2. 示例#

本示例设置摄像头输出320x240灰度图像，使用image.find_apriltags来识别AprilTags

小技巧

如果识别成功率低，可尝试修改摄像头输出的mirror和flip设置

# AprilTags Example
#
# This example shows the power of the CanMV Cam to detect April Tags.

import time, math, os, gc, sys

from media.sensor import *
from media.display import *
from media.media import *

DETECT_WIDTH = 320
DETECT_HEIGHT = 240

# Note! Unlike find_qrcodes the find_apriltags method does not need lens correction on the image to work.

# The apriltag code supports up to 6 tag families which can be processed at the same time.
# Returned tag objects will have their tag family and id within the tag family.

tag_families = 0
tag_families |= image.TAG16H5 # comment out to disable this family
tag_families |= image.TAG25H7 # comment out to disable this family
tag_families |= image.TAG25H9 # comment out to disable this family
tag_families |= image.TAG36H10 # comment out to disable this family
tag_families |= image.TAG36H11 # comment out to disable this family (default family)
tag_families |= image.ARTOOLKIT # comment out to disable this family

# What's the difference between tag families? Well, for example, the TAG16H5 family is effectively
# a 4x4 square tag. So, this means it can be seen at a longer distance than a TAG36H11 tag which
# is a 6x6 square tag. However, the lower H value (H5 versus H11) means that the false positve
# rate for the 4x4 tag is much, much, much, higher than the 6x6 tag. So, unless you have a
# reason to use the other tags families just use TAG36H11 which is the default family.

def family_name(tag):
    if(tag.family() == image.TAG16H5):
        return "TAG16H5"
    if(tag.family() == image.TAG25H7):
        return "TAG25H7"
    if(tag.family() == image.TAG25H9):
        return "TAG25H9"
    if(tag.family() == image.TAG36H10):
        return "TAG36H10"
    if(tag.family() == image.TAG36H11):
        return "TAG36H11"
    if(tag.family() == image.ARTOOLKIT):
        return "ARTOOLKIT"

sensor = None

try:
    # construct a Sensor object with default configure
    sensor = Sensor(width = DETECT_WIDTH, height = DETECT_HEIGHT)
    # sensor reset
    sensor.reset()
    # set hmirror
    # sensor.set_hmirror(False)
    # sensor vflip
    # sensor.set_vflip(False)

    # set chn0 output size
    sensor.set_framesize(width = DETECT_WIDTH, height = DETECT_HEIGHT)
    # set chn0 output format
    sensor.set_pixformat(Sensor.GRAYSCALE)

    # use hdmi as display output, set to VGA
    # Display.init(Display.LT9611, width = 640, height = 480, to_ide = True)

    # use hdmi as display output, set to 1080P
    # Display.init(Display.LT9611, width = 1920, height = 1080, to_ide = True)

    # use lcd as display output
    # Display.init(Display.ST7701, to_ide = True)

    # use IDE as output
    Display.init(Display.VIRT, width = DETECT_WIDTH, height = DETECT_HEIGHT, fps = 100)

    # init media manager
    MediaManager.init()
    # sensor start run
    sensor.run()

    fps = time.clock()

    while True:
        fps.tick()

        # check if should exit.
        os.exitpoint()

        img = sensor.snapshot()
        for tag in img.find_apriltags(families=tag_families):
            img.draw_rectangle([v for v in tag.rect()], color=(255, 0, 0))
            img.draw_cross(tag.cx(), tag.cy(), color=(0, 255, 0))
            print_args = (family_name(tag), tag.id(), (180 * tag.rotation()) / math.pi)
            print("Tag Family %s, Tag ID %d, rotation %f (degrees)" % print_args)

        # draw result to screen
        Display.show_image(img)
        gc.collect()

        print(fps.fps())
except KeyboardInterrupt as e:
    print(f"user stop")
except BaseException as e:
    print(f"Exception '{e}'")
finally:
    # sensor stop run
    if isinstance(sensor, Sensor):
        sensor.stop()
    # deinit display
    Display.deinit()

    os.exitpoint(os.EXITPOINT_ENABLE_SLEEP)
    time.sleep_ms(100)

    # release media buffer
    MediaManager.deinit()

提示

具体接口定义请参考 find_apriltags

3. 识别AprilTags例程讲解

目录

3. 识别AprilTags例程讲解#

1. 概述#

2. 示例#